Vector Velocity and Coulomb's Law

1. The problem statement, all variables and given/known data
Three charged particles are placed at each of three corners of an equilateral triangle whose sides are of length 3.5 cm. Two of the particles have a negative charge: q_1 = -8.0 nC and q_2 = -16.0 nC. The remaining particle has a positive charge, q_3 = 8.0 nC. Assume that particle 3 is no longer fixed to a corner of the triangle and is now allowed to move. In what direction would particle 3 move the instant after being released???

The velocity of the body will be directed with the force as the body was initially at rest
F gives the direction of acceleration a
a = (change in velocity ) /time
a=(v-0)/t
a is directed towards F but a, v, and t are unknowns